The present invention relates generally to multilayer films, and methods of using same, especially to produce a packaged food product comprising cooked meat having a flavorant and/or fragrance and/or odor absorbent and/or colorant and/or antimicrobial, and/or antioxidant, and/or chelating agent therewith.
The food packaging industry uses packaging films from which bags and casings are made which are such that they may be used in cook-in applications, i.e., uses in which a food product is packaged in the film, following which the food product is cooked while packaged in the film. The term xe2x80x9ccook-in,xe2x80x9d as used herein with respect to packaging materials such as films, refers to packaging material structurally capable of withstanding exposure to cook-in time-temperature conditions while surrounding a food product. Cook-in foods are foods cooked in the package. The cooked product can be distributed to the customer in the original bag or the bag removed and the meat portioned for repackaging. Cook-in time-temperature conditions typically refer to a long slow cook, for example submersion in hot water at 131 xc2x0 F. to 149xc2x0 F. for 12 hours. However, cook-in can include submersion at from 135xc2x0 F. to 212xc2x0 F. for 2-12 hours, or from 158xc2x0 F. to 212xc2x0 F. for from 1-4 hours.
During cook-in, the package should maintain seal integrity, i.e., any heat-sealed seams should resist being pulled apart during cook-in. Preferably, the film is heat sealable to itself Additionally, the packaging film substantially conforms to the packaged food product. Preferably, this substantial conformability is achieved by the film being heat shrinkable under these conditions so as to form a tightly fitting package. In other words, in an advantageous embodiment, the film is heat-shrinkable under time-temperature conditions of cook-in, i.e., the film possesses sufficient shrink energy such that submerging the packaged food product in hot water will shrink the packaging film snugly around the packaged product, representatively up to about 55% monoaxial or biaxial shrinkage at 185xc2x0 F. Also, during cook-in the film should have food product adherence to restrict xe2x80x9ccook-out,xe2x80x9d i.e., the collection of juices between the surface of the contained food product and the meat-contact surface of the packaging material, cook-out is commonly referred to as xe2x80x9cpurge.xe2x80x9d In this manner, product yield is increased by the food product retaining moisture, and the aesthetic appearance of the packaged product is not diminished by the presence of the purge.
For ham, beef, turkey, and other meat products, it is often desirable to expose the surface of the meat product to an additive, to simply coat or even suffuse the additive into the surface of the meat product. The additive can be, for example, a colorant or flavorant. The use of a smoke-containing additive is particularly common, the smoke providing both a flavor effect and a color effect to the meat product.
If the surface of the product is to be exposed to an additive, for example to produce a smoked meat product, it has for some time been standard practice in the industry to first package the meat product in a film, followed by cooking the meat product while it is packaged, followed by removing the cooked meat from the package and placing the meat in a smokehouse to impart smoke coloration and flavor. The smoked meat product is thereafter repackaged in another film, and shipped to a wholesaler, retailer, or consumer.
In addition, the unpackaging, smoking, and repackaging of the cooked meat product exposes the cooked meat product to microbial contamination, resulting in shorter shelf life for the cooked meat product. However, the need to unpackage, smoke, and repackage the meat product is a labor intensive, expensive process for the manufacturer of the smoked cooked meat product. Furthermore, the smoking step is inefficient in that only about 70% of the smoke is effective as a flavorant/colorant, with the remaining 30% of the smoke accumulating on non-food surfaces in the smokehouse, necessitating cleaning, etc. and generating waste.
Thus, it would be desirable to provide a packaged product without having to package, cook, unpackage, smoke, and repackage, together with avoiding the handling required for each of these operations. It would be desirable to entirely avoid the need to unpackage and repackage and thereby avoid the potential for microbiological contamination, together with avoiding the waste from discarding the original package, the inefficiency and waster from the smoking in a smokehouse, as well as to avoid the lower shelf life of the finally-packaged product, resulting from microbiological contamination due to excess handling of the cooked meat product.
The present invention solves the longstanding problem described above, by providing a film which can be coated with an additive which is transferred to a product during cook-in, while avoiding the handling, waste, inefficiency, and contamination generated by the steps of unpackaging, smoking, and repackaging in accordance with the prior art. Moreover, during cooking of a food product surrounded by the film, the binder and additive are both transferred from the film to the food product. After cooking, the film can be stripped off of the food product cleanly (less the binder and additive, which are transferred to the food), i.e., without any food (meat) pull-off, even though the coating prevents or reduces purge. Thus, the film according to the invention is capable of being used during cook-in to prevent or reduce purge, provide a uniform transfer of additive(s) to the surface of the meat product, while at the same time allowing a clean separation of the cooked food (especially meat) from the film, without tear-off.
In addition, the film of the present invention can be easily manufactured, i.e., the additive-containing coating can be applied to the film using coating or printing technology, such as gravure coating or printing, lithographic coating or printing, etc. The coating can be printed onto the film in the pattern of the product or a portion of the product, while avoiding printing the coating onto areas to be sealed. The film of the present invention is also more efficient than, for example, application of smoke to meat in a smokehouse, because substantially all of the liquid smoke coating is transferred to the meat, without waste. The film is also dry, so that it can be prepared with the additive(s) present, and stored before use, unlike films which have a wet coating thereon.
The present invention resulted from the discovery that films can be uniformly coated with certain binders in a form which are not quick to become hydrated or dissolved at the conditions of use. That is, the invention resulted from the discovery of binders which, together with crosslinkers, control the initial adhesion of the additive to the film, reduce the rate of hydration of the coating and the release of the additive, and further the binding of the coating to, for example, a cooked meat product during the cooking step. The result is that the additive-containing coating is present on the film in a form which prevents or reduces smearing of the coating when, for example, a coated film casing is filled with the meat product or flowing of the additive during cooking of the product, i.e. resulting in a mottled distribution of the additive. It was also discovered that the binder holds an additive which is released during cook-in, so that the meat product is flavored/colored in a desired manner and degree, without having to unpackage, treat, and repackage the product. In this manner, the shelf life of the resulting packaged product is increased relative to packaged products produced in accordance with the prior art method which requires unpackaging and repackaging. In addition, certain binders were discovered to be better than others, as were particular combinations of binders, such as the combination of hydroxypropyl starch with a crosslinking agent (e.g., liquid smoke), together, optionally, with fibrinogen as a second binder. In addition, particular cooking procedures were discovered which result in reduced purge when using a film in accordance with the present invention. Moreover, the pH of the coating composition was discovered to have an effect on the quantity of purge loss as well as the quality of the transfer of an additive from the film to meat packaged in the film. For example, a pH of from about 2 to 6 is considered to be a preferred range for the pH of the coating formulation used to coat a substrate thermoplastic film.
As a first aspect, the present invention pertains to a multilayer film comprising a first layer and a second layer. The first layer comprises: (i) an additive comprising at least one member selected from the group consisting of flavor, fragrance, colorant, antimicrobial agent, antioxidant, chelating agent, and odor absorbent, (ii) a binder comprising at least one member selected from the group consisting of polysaccharide and protein, and (iii) a crosslinking agent comprising a compound with at least two carbonyl groups. The second layer comprises a non-water-soluble thermoplastic polymer comprising at least one member selected from the group consisting of polyolefin, polyamide, polyester, polyvinylidene chloride, polyvinyl chloride, and polystyrene. Each of the additive, binder, and crosslinking agent are present throughout a thickness of the first layer. The presence of a crosslinking agent results in a crosslinked polymer network.
Preferably, the additive comprises at least one member selected from the group consisting of caramel, liquid smoke, FDandC Blue No 1, FDandC Blue No 2, FDandC Green No 3, FDandC Green No 6, FDandC Orange B, FDandC Red No 3, FDandC Red No 40, FDandC Yellow No 5, FDandC Yellow No 6, a lake of one or more FDandC colorant, natural brown, annatto extract, beet powder, canthaxanthin, xcex2-Apo-8xe2x80x2-carotenal, carotene, cochineal extract, carmine, grape color extract, synthetic iron oxide, paprika, riboflavin, and titanium oxide, malt, natural colorant, spice, bacteriocin, allyisothiocyanate, monolaurin, 1-[2-(2,4-dichlorophenyl)-2-(propenyloxy)ethyl]-1H-imidazole, silver, benzoic-acid, benzoate, hydroxycinnamic acid derivative, essential oil, sorbic acid, salt of sorbic acid, benzoate, methyl p-hydroxybenzoate, propyl p-hydroxybenzoate, p-hydroxybenzoic acid, sodium benzoate, propionic acid, salt of propionic acid, sodium lactate, dimethyl dicarbonate, diethyl dicarbonate, sulfite, diethyl pyrocarbonate, EDTA, butylated hydroxyanisole, butylated hydroxytoluene, propyl gallate, dilauryl thiodipropionate, thiodipropionic acid, gum guaiac, tocopherol, acetate, citrate, gluconate, oxystearin, ortho-phosphate, meta-phosphate, pyro-phosphate, polyphosphate, phytate, sorbitol, tartrate, thiosulfate, and lysozyme,
Preferably, the additive comprises a colorant and the multilayer film, when subjected to a Standard Mottling Test, exhibits a Gray Scale standard deviation of less than about 20; more preferably, from about 0 to 20; still more preferably, from about 0 to 19; yet still more preferably, from about 0 to 18; even yet still more preferably, from about 12 to 18; even yet still more preferably, from about 0 to 17; even yet still more preferably, from about 0 to 16; even yet still more preferably, from about 0 to 15; even yet still more preferably, from about 0 to 14; even yet still more preferably, from about 0 to 13; even yet still more preferably, from about 0 to 12.
Preferably, the binder comprises at least one member selected from the group consisting of alginate, methyl cellulose, hydroxypropyl starch, hydroxypropylmethyl starch, hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose, cellulose esterified with 1-octenyl succinic anhydride, chitin, and chitosan, gliadin, glutenin, globulin, albumin (especially in the form of gluten), prolamin (especially corn zein), thrombin, pectin, canageenan, konjac flour-glucomannin, fibrinogen, casein (especially casein milk protein), soy protein (especially soy protein isolates), whey protein (especially whey milk protein), and wheat protein.
Another preferred grouping of binders comprises at least one member selected from the group consisting of: (A) polysaccharide esterified with at least one member selected from the group consisting of: acetic anhydride, propionic anhydride, alkyl-propionic anhydride, butyric anhydride, alkyl-butyric anhydride, succinic anhydride, alkyl-succinic anhydride, maleic anhydride, alkyl-maleic anhydride, adipic anhydride, alkyl-adipic anhydride, and vinyl acetate; and (B) polysaccharide etherified with at least one member selected from the group consisting of acrolein, epichlorihydrin, ethylene glycol, ethylene glycol oligomer, propylene glycol, propylene glycol oligomer, ethylene oxide, and propylene oxide.
Yet another preferred first layer comprises at least two different binders, i.e.: (A) a first binder comprising at least one member selected from the group consisting of alginate, methyl cellulose, hydroxypropyl starch, hydroxypropylmethyl starch, hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose, cellulose esterified with 1-octenyl succinic anhydride, chitin, and chitosan; and (B) a second binder comprising at least one member selected from the group consisting of gliadin, glutenin, globulin, albumin (especially in the form of gluten), prolamin (especially corn zein), thrombin, pectin, canageenan, konjac flour-glucomannin, fibrinogen, casein (especially casein milk protein), soy protein, whey protein (especially whey milk protein), and wheat protein. More preferably, the binder comprises hydroxypropyl starch.
Another preferred group of binders comprises at least one member selected from the group consisting of: (A) at least one member selected from the group consisting of polysaccharide esterified with an anhydride of the formula: [CH3(CH2)nxe2x80x94CO]2xe2x80x94O, where n=from 0 to 6, as well as alkyl-substituted anhydrides thereof; (B) CH3(CH2)nxe2x80x94COCl, where n=from 0 to 6; (C) alkyl-substituted acid chlorides of CH3(CH2)nxe2x80x94COCl, where n=from 0 to 6, (D) modified polysaccharide which results from the etherification of a base polysaccharide with at least one member selected from the group consisting of acrolein, epichlorohydrin, ethylene glycol, ethylene glycol oligomer, propylene glycol, propylene glycol oligomer, ethylene oxide, and propylene oxide.
Preferably, the second layer comprises at least one member selected from the group consisting of polyamide 6, polyamide 66, polyamide 9, polyamide 10, polyamide 11, polyamide 12, polyamide 69, polyamide 610, polyamide 612, polyamide 6I, polyamide 6T, polyamide MXD6, copolyamide, polyethylene homopolymer, ethylene/alpha-olefin copolymer, anhydride-modified ethylene/alpha-olefin copolymer, ethylene/vinyl acetate copolymer, ethylene/acrylic acid copolymer, ionomer (especially ionomers of ethylene/methacrylic acid and ethylene/acrylic acid), ethylene/methacrylic acid copolymer, anhydride-modified ethylene/methacrylic acid copolymer, polypropylene homopolymer, propylene/C4-10 alpha-olefin copolymer, polyethylene terephthalate, PETG, and polyalkylhydroxy acid.
Preferably, the multilayer film has a total free shrink (i.e., L+T) of from about 0 to 10 percent at a temperature of 185xc2x0 F.; more preferably, from about 10 to 150%; still more preferably, from about 10 to 100%.
Preferably, the additive is bound to the binder with at least one member selected from the group consisting of a covalent bond, an ionic bond, a hydrogen bond, and a dipole-dipole interaction.
Preferably, the crosslinking agent comprises at least one member selected from the group consisting of malose, glutaraldehyde, glyoxal, dicarboxylic acid, ester of dicarboxylic acid, urea formaldehyde, melamine formaldehyde, trimethylol-melamine, organic compound containing at least 2 sulfhydryl groups, and a component in liquid smoke comprising at least two carbonyl groups.
Preferably, the second layer is directly adhered to the first layer.
Preferably, the film further comprises a third layer which is between the first layer and the second layer. This third layer can serve as a primer which is applied to the second layer, for the subsequent application of the first layer. Additionally or alternatively, the third layer can contain an additive, such as one or more of the additives which can be present in the first layer, and/or a release agent, and/or a crosslinking agent. Preferably, the third layer comprises at least one member selected from the group consisting of polysaccharide and protein; more preferably, at least one member selected from the group consisting of: alginate, methyl cellulose, hydroxypropyl starch, hydroxypropylmethyl starch, hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose, cellulose esterified with 1-octenyl succinic anhydride, chitin, and chitosan, gliadin, glutenin, globulin, albumin (especially in the form of gluten), prolamin (especially corn zein), thrombin, pectin, canageenan, konjac flour-glucomannin, fibrinogen, casein (especially casein milk protein), soy protein, whey protein (especially whey milk protein), and wheat protein.
Preferably, the multilayer film further comprises a third layer, with the first layer being between the second layer and the third layer. Preferably, the third layer comprises at least one member selected from the group consisting of polysaccharide and protein. More preferably, at least one member selected from the group consisting of alginate, methyl cellulose, hydroxypropyl starch, hydroxypropylmethyl starch, hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose, cellulose esterified with 1-octenyl succinic anhydride, chitin, and chitosan, gliadin, glutenin, globulin, albumin (especially in the form of gluten), prolamin (especially corn zein), thrombin, pectin, canageenan, konjac flour-glucomannin, fibrinogen, casein (especially casein milk protein), soy protein, whey protein (especially whey milk protein), and wheat protein. This third layer, which serves as an xe2x80x9covercoatxe2x80x9d over the first layer, can further comprise an additive, such as one or more of the additives present in the first layer, and/or a meat adhesion enhancing additive and/or a crosslinking agent. Preferably, the multilayer film further comprises a fourth layer which is between the first layer and the second layer. Preferably, the fourth layer serves as a primer layer, as described above.
Preferably, the multilayer film, when subjected to a Standard Mottling Test, exhibits a mottling level of from about 1to about 2.5.
Preferably, the first layer further comprises a plasticizer. Preferably, the plasticizer comprises at least one member selected from the group consisting of polyol, sodium citrate, and triethyl citrate.
Preferably, the multilayer film further comprises a third layer comprising at least one member selected from the group consisting of polyolefin, polyamide, and polyester. More preferably, the third layer comprises at least one member selected from the group consisting of ethylene/vinyl alcohol copolymer, vinylidene chloride copolymer, polyamide, polyvinyl alcohol, polyhydroxyaminoether, and polyalkylene carbonate, ethylene/acrylic acid copolymer, polyethylene terephthalate, and ionomer. Preferably, the third layer is an inner layer, and the multilayer film further comprises a fourth layer comprising at least one member selected from the group consisting of polyolefin, polyamide, and polyester; more preferably ethylene/vinyl alcohol copolymer, vinylidene chloride copolymer, polyamide, polyvinyl alcohol, polyhydroxyaminoether, and polyalkylene carbonate, ethylene/acrylic acid copolymer, polyester, and polyethylene terephthalate.
Preferably, the second film layer serves as a seal layer and comprises at least one member selected from the group consisting of polyolefin, polyamide, and polyester, and preferably, the film further comprises: (i) a third layer which serves as an O2-barrier layer comprising at least one member selected from the group consisting of at least one member selected from the group consisting of ethylene/vinyl alcohol copolymer, polyvinylidene chloride, polyamide, polyalkylene carbonate, polyvinyl alcohol, and polyester; (ii) a fourth film layer which serves as a first tie layer and which is on a first side of the O2-barrier layer and which comprises at least one member selected from the group consisting of modified ethylene/alpha-olefin copolymer, modified ethylene/unsaturated ester copolymer, modified ethylene/unsaturated acid copolymer, polystyrene and polyurethane; and (iii) a fifth film layer which serves as a second tie layer and which is on a second side of the O2-barrier layer and which comprises comprising at least one member selected from the group consisting of modified ethylene/alpha-olefin copolymer, modified ethylene/unsaturated ester copolymer, modified ethylene/unsaturated acid copolymer, polystyrene and polyurethane; and (iv) a sixth film layer which serves as an abuse layer and which comprises at least one member selected from the group consisting of polyolefin, polyamide, polyester, and polyurethane. More preferably, the film further comprises: (i) a seventh film layer which serves as a strength layer and which is between the second layer and the fourth layer, and which comprises at least one member selected from the group consisting of polyolefin, polyamide, polyester, and polyurethane; (ii) a eighth film layer which serves as a strength and balance layer and which is between the fifth layer and the sixth layer, and which comprises at least one member selected from the group consisting of polyolefin, polyamide, polyester, and polyurethane; and (iii) a ninth film layer which serves as a strength and moisture barrier layer and which between the fifth layer and the sixth layer, and which comprises polyamide.
As a second aspect, the present invention pertains to a process for preparing a cooked food product, comprising: (A) packaging a food product in a multilayer film in accordance with the first aspect of the present invention, and (B) cooking the food product while the food product is packaged in the multilayer film. Preferably, the food product comprises at least one member selected from the group consisting of beef, pork, chicken, turkey, fish, and meat-substitute. Preferably, the food is cooked at a temperature of from about 145xc2x0 F. to 205xc2x0 F. for a duration of from about 1 to 12 hours.
As a third aspect, the present invention is directed to a process for preparing a cooked food product, comprising: (A) packaging a food product in a multilayer film in accordance with the first aspect of the present invention, and (B) cooking the food product at a temperature of from about 170xc2x0 F. to 260xc2x0 F. for a duration of from about 1to 20 minutes, followed by cooking the food product at a temperature of from about 145xc2x0 F. to 205xc2x0 F. for a duration of from about 1 to 12 hours.
As a fourth aspect, the present invention is directed to a process for making a coated multilayer film, comprising: (A) coating an outer surface of a substrate film with a film-forming coating composition comprising: (i) water; (ii) an additive comprising at least one member selected from the group consisting of flavor, fragrance, colorant, antimicrobial agent, antioxidant, chelating agent, and odor absorbent, (iii) a binder comprising at least one member selected from the group consisting of polysaccharide and protein, and (iv) a crosslinking agent comprising a compound having at least two carbonyl groups; and (B) drying the coating composition whereby the composition becomes a first film layer, the substrate film comprising at least a second film layer. The substrate film comprises at least one member selected from the group consisting of polyolefin, polyamide, polyester, polyvinylidene chloride, polyvinyl chloride, and polystyrene. Preferably, the coating composition is applied to the film using at least one member selected from the group consisting of roll (preferably comma roll, obtained from Hirano Tecseed, of Charlotte, N.C.), gravure, flexographic, meyer rod, reverse angle doctor blade, knife over roll, two roll reverse, three roll reverse, comma roll, and lip coating.
As a fifth aspect, the present invention is directed to an article comprising a multilayer film in accordance with the first aspect of the present invention, wherein the second layer is sealed to itself or another film. Preferably, the first layer extends over (i.e., covers) only a portion of the second layer. Preferably, the article comprises at least one member selected from the group consisting of a bag, a backseamed casing, a pouch, and a thermoformed article. More preferably, the article comprises at least one member selected from the group consisting of fin-sealed backseamed casing, lap-sealed backseamed casing, butt-sealed backseamed casing, side-seal bag, end-seal bag, pouch, and perimeter sealed thermoformed article.
As a sixth aspect, the present invention is directed to a packaged product comprising: (A) a film comprising a non-water-soluble thermoplastic polymer comprising at least one member selected from the group consisting of polyolefin, polyamide, polyester, polyvinylidene chloride, polyvinyl chloride, and polystyrene; (B) a cooked meat product comprising at least one member selected from the group consisting of beef, pork, chicken, turkey, fish, and meat-substitute; and (C) a layer between the film and the cooked meat product. The C layer comprises: (i) an additive comprising at least one member selected from the group consisting of flavor, fragrance, colorant, antimicrobial agent, antioxidant, chelating agent, and odor absorbent, (ii) a binder comprising at least one member selected from the group consisting of polysaccharide and protein, and (iii) a crosslinking agent comprising a compound with at least two carbonyl groups. In the C layer, each of the additive, binder, and crosslinking agent are present throughout a thickness of the first layer. Preferably, the layer between the film and the cooked meat product is preferentially adhered to the meat product, i.e., is adhered to the meat product to a degree so that upon removing the film from the meat product, the C layer remains adhered to the meat product, rather than to the film.